How big a sample?

Students need experience in comparing the results from samples with results from the full population. Comparisons should be made with samples of various sizes and the population (or much larger samples).

Useful activities to explore sample size require students to sample and re-sample to demonstrate the naturally occurring variation in small samples.

Other useful activities compare samples of various sizes from the one larger population. The figure below shows a stacked dot plot of the full population of 813 compared to a stacked dot plot of a sample of 100.

Stacked box plot showing approximately normal distribution of both the population and the sample.

Distribution of the population compared to a sample.

The activity Increasing Sample Size is based around a video. It demonstrates that the distribution of data from a small sample can resemble the distribution of the data from the larger population.

Media reports often focus on one person's opinion and do not include data to support a claim. Such reports can lead to further investigations to determine if a larger appropriate sample reflects the same results.

Curriculum links

Year 8: Investigate techniques for collecting data, including census, sampling and observation

Year 8: Explore the practicalities and implications of obtaining data through sampling using a variety of investigative processes